Re: [PATCH REPOST 5/5] mm/damon/vaddr: support pgidle_unset probe filter type

[Kunwu Chan <kunwu.chan@gmail.com>]

On Wed,  9 Sep 2026 07:04:07 -0700 SJ Park <sj@kernel.org> wrote:

> DAMON virtual address space operation set (vaddr) does not support
> pgidle_unset probe filter type.  Add the support.
> 
> Signed-off-by: SJ Park <sj@kernel.org>
> ---
>  mm/damon/vaddr.c | 55 ++++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 48 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
> index 45239f05e113b..9a38dc89a156e 100644
> --- a/mm/damon/vaddr.c
> +++ b/mm/damon/vaddr.c
> @@ -522,13 +522,49 @@ static void damon_va_prep_probes(struct damon_ctx *ctx, bool set_samples)
>  	}
>  }
>  
> -static bool damon_va_filter_pass(struct folio *folio, struct damon_probe *p)
> +static bool damon_va_young_addr(struct folio *folio, pte_t *pte, pmd_t *pmd,
> +		struct mm_struct *mm, unsigned long addr)
> +{
> +	bool young = false;
> +
> +	if (pte)
> +		young = pte_young(*pte);
> +	else if (pmd)
> +		young = pmd_young(*pmd);

Hi SJ,
I see that all callers already check pte_present() / pmd_present()
before calling this helper, so I don't see a correctness issue here.

However, the other DAMON young/accessed helpers, such as
damon_pte_young(), damon_hugetlb_young(), and the PMD path in
damon_folio_young_one(), keep the present check together with the
young check.

Would it make sense to keep the same check here for consistency?

Thanks,
Kunwu

> +	young = young || !folio_test_idle(folio) ||
> +		mmu_notifier_test_young(mm, addr);
> +	return young;
> +}
> +
> +static bool damon_va_filter_match(struct damon_filter *filter,
> +		struct folio *folio, pte_t *pte, pmd_t *pmd,
> +		struct mm_struct *mm, unsigned long addr)
> +{
> +	bool matched = false;
> +
> +	switch (filter->type) {
> +	case DAMON_FILTER_TYPE_PGIDLE_UNSET:
> +		if (!folio)
> +			matched = false;
> +		else
> +			matched = damon_va_young_addr(folio, pte, pmd, mm,
> +					addr);
> +		break;
> +	default:
> +		return damon_ops_filter_match(filter, folio);
> +	}
> +	return matched == filter->matching;
> +}
> +
> +static bool damon_va_filter_pass(struct folio *folio, struct damon_probe *p,
> +		pte_t *pte, pmd_t *pmd, struct mm_struct *mm,
> +		unsigned long addr)
>  {
>  	struct damon_filter *f;
>  	bool pass = true;
>  
>  	damon_for_each_filter(f, p) {
> -		if (damon_ops_filter_match(f, folio)) {
> +		if (damon_va_filter_match(f, folio, pte, pmd, mm, addr)) {
>  			pass = f->allow;
>  			break;
>  		}
> @@ -543,13 +579,15 @@ struct damon_va_probe_walk_private {
>  };
>  
>  static void damon_va_probe_folio(struct damon_ctx *ctx,
> -		struct damon_region *r, struct folio *folio)
> +		struct damon_region *r, struct folio *folio,
> +		pte_t *pte, pmd_t *pmd, struct mm_struct *mm)
>  {
>  	struct damon_probe *probe;
>  	int i = 0;
>  
>  	damon_for_each_probe(probe, ctx) {
> -		if (damon_va_filter_pass(folio, probe))
> +		if (damon_va_filter_pass(folio, probe, pte, pmd, mm,
> +					r->sampling_addr))
>  			r->probe_hits[i]++;
>  		i++;
>  	}
> @@ -574,7 +612,8 @@ static int damon_va_probe_pmd_entry(pmd_t *pmd, unsigned long addr,
>  		folio = vm_normal_folio_pmd(walk->vma, addr, pmde);
>  		if (!folio)
>  			goto huge_out;
> -		damon_va_probe_folio(priv->ctx, priv->r, folio);
> +		damon_va_probe_folio(priv->ctx, priv->r, folio, NULL, &pmde,
> +				walk->vma->vm_mm);
>  
>  huge_out:
>  		spin_unlock(ptl);
> @@ -591,7 +630,8 @@ static int damon_va_probe_pmd_entry(pmd_t *pmd, unsigned long addr,
>  	folio = vm_normal_folio(walk->vma, addr, ptent);
>  	if (!folio)
>  		goto out;
> -	damon_va_probe_folio(priv->ctx, priv->r, folio);
> +	damon_va_probe_folio(priv->ctx, priv->r, folio, &ptent, NULL,
> +			walk->vma->vm_mm);
>  
>  out:
>  	pte_unmap_unlock(pte, ptl);
> @@ -615,7 +655,8 @@ static int damon_va_probe_hugetlb_entry(pte_t *pte, unsigned long hmask,
>  
>  	folio = pfn_folio(pte_pfn(entry));
>  	folio_get(folio);
> -	damon_va_probe_folio(priv->ctx, priv->r, folio);
> +	damon_va_probe_folio(priv->ctx, priv->r, folio, &entry, NULL,
> +			walk->vma->vm_mm);
>  	folio_put(folio);
>  
>  out:
> -- 
> 2.47.3
> 

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